Published online: Sep 09, 2009
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"Worst case scenario-if no preventative steps had been taken, then yes, we could have had 100 percent crop loss of 68,000 acres of potatoes," notes Amanda Gevens, plant pathologist with University of Wisconsin-Madison and the University of Wisconsin Extension, in reference to the spread of the late blight fungus from the eastern seaboard to the Midwest.
"But Wisconsin potato growers have been very vigilant-taking preventative measures such as applying fungicides and having professional scouts inspect their fields. Because of the late blight outbreaks in the late 1990s and early 2000s, we
had the experience and knowledge to contain late blight and limit the risk to the current crop and next year's seed potatoes."

Adds AJ Bussan, Associate Professor in the Department of Horticulture at the University of Wisconsin- Madison, "At this point, the volume of stored potatoes does not appear to be in jeopardy. All the growers have been taking preventative action for the last six to eight weeks, and we've only had a single case in which late blight was found in a production field." The field, located in Portage County, had one small sector of blight located in a far corner of the field. The plants were immediately destroyed, as were those in a buffer zone surrounding the infested plants. Fungicides were used to stop subsequent lesions on plants that were found by scouts. The lesions were not active - thus preventing the spores from spreading by air. No potatoes were harvested from the infected plants.

Late blight, responsible for the great famine in Ireland in the 1840s and 1850s, has the potential to destroy crops around the nation because the spores can travel long distances via air. "But this isn't the nineteenth-century," notes Gevens. "We have the know-how and the tools to contain infestations. Preventative measures, including those of commercial growers and home gardeners, have been key."

Another factor that helped prevent a widespread outbreak is timing. "We've gotten the tail end of this-it started in June on the east coast. Now, in September, growers are already performing vine kill, which helps the potato skin `set up'-or thicken. This makes the potato more resistant to disease." By killing the green foliage, growers not only prepare their crop for harvest, but eliminate the green plant material that late blight needs to survive."

Ranked third in the nation for potato production, Wisconsin harvested 2.3 billion pounds of potatoes in 2008, generating over $300 million in product dollars for farmers and shippers. Agribusiness in Wisconsin generated $51.5 billion in economic activity and provided jobs for 420,000 people-about one out of every eight residents works in a job related to farming.